neowin[.]net/news/microsoft-and-intel-issue-warning-about-mmio-stale-data-vulnerability-on-windows-11-10/
support.microsoft[.]com/en-us/topic/kb4093836-summary-of-intel-microcode-updates-08c99af2-075a-4e16-1ef1-5f6e4d8637c4
Intel and Microsoft have published fresh security advisories regarding a list of new CPU vulnerabilities affecting Intel Core processors. These security flaws are related to a CPU's memory-mapped I/O (MMIO) and hence are called "MMIO Stale Data Vulnerabilities" collectively. A threat actor, upon successful exploitation of a vulnerable system, can read privileged information on a compromised system.
Intel talks about new microcode, while the Linux kernel has already been patched -- phoronix[.]com/scan.php?page=news_item&px=MMIO-Stale-Data-Vulnerabilities -- so it's unclear whether a future Windows patch will fix the issue or if it will mean new BIOS firmware updates. The worry IMHO is that new firmware, which could be pushed out via Windows Update, will hurt performance like it did with Spectre.